The development of Micro-Electro-Mechanical Systems (MEMS) technology has enabled manufacturers to produce inertial sensors (e.g., accelerometers) of sufficiently small size, cost, and power consumption to fit into portable electronic devices. Such inertial sensors can be found in a limited number of commercial electronic devices such as cellular phones, portable music players, pedometers, game controllers, and portable computers.
Step counting devices (e.g., pedometers) are used to monitor an individual's daily activity by keeping track of the number of steps that he or she takes. In general, step counting devices are clipped to a user's hip, and do not accurately count steps when placed elsewhere on a user's body.
Some step counting devices include an inertial sensor placed at specific locations on a user's body (e.g., in a user's shoe). Inertial sensors placed in a user's shoe (known as foot pods) may be used to determine a user's speed and distance because the foot comes to rest once for each step. However, conventional devices are not able to accurately determine distance and speed based on inertial sensors placed elsewhere on a user's body. Such conventional devices generally measure only a number of steps walked.